Effects Of Wheat Straw Application On Yield Formation In Rice And Greenhouse Gas Emission And Effects Of Fertilizer And Water Management

Straw application has become the most extensive and direct way to deal with straw in agricultural production,and it has a close relationship with environment change due to its effect of greenhouse gas emission.Jiangsu,one of the typical provinces,is using the planting pattern of wheat-rice rotation.It has formed a unique paddy soil ecosystem throughout the rice season after returning wheat straw to the field due to the intensive production cycle,large straw output and short time of soil digestion in this area,the effect on rice growth also has its own way.The long-term research on straw application has formed a considerable accumulation,which basically forms the understanding of the effects of straw application on soil and crop growth.However,there are many different views related to the understanding of effects on soil,environmental and crop growth caused by straw application in different researches.At the same time,cultivation measures for the effects of wheat straw application also need deeper analysis.In order to discuss the effects of wheat straw application on rice growth and its characteristics and analyze the change of soil properties and greenhouse gas emission at the same time,this paper researched the process of rice growth after returning preceding wheat straw to the field.Furthermore,this paper researched the effects of panicle fertilizer and irrigation modes on the effect of straw application.It is expected that the research will provide the necessary theories for correctly evaluating the effect of straw application on the condition of wheat-rice rotation,and it is also expected that the research will provide experimental basis for establishing the technical system with the fertility regulation and high efficiency.The main results are as follows:1.Straw application has an obvious pre-suppression effect on rice growth.There is a time extension in seedling survival after returning straw to the field and the growth speeds of tiller and seedling are slow in the early stage.But the negative effect recovers rapidly along with the rice growth and the capacity of dry matter production is higher in the middle and late stage.Finally,rice yield has a certain degree of improvement.The positive effect of straw application is mainly reflected in the yield component decided by rice growth in the middle and late stage,and it has a significant effect on the number of grain per panicle and seed setting rate particularly.The effect of straw application is obviously different among varieties,and the growth of hybrid rice is more obvious.It is significant for suitable panicle fertilizer and alternate wetting and moderate drying irrigation to increase rice yield.In a way,they can promote the positive effect of straw application.2.Straw application significantly promotes the physiological activity of rice in the middle and late stage.After returning straw to the field,leaf's photosynthetic rate and transpiration rate are enhanced in heading stage and grain filling stage,at the same time,the activity of nitrogen metabolism enzymes are enhanced in heading stage.After returning straw to the field,the root activity of rice is significantly increased,and it is closely correlated with the increase of rice yield.It is obvious for suitable panicle fertilizer and alternate wetting and moderate drying irrigation to enhance leaf's photosynthetic rate in heading stage and grain filling stage,at the same time,the root activity is enhanced in heading stage.In a way,they can promote the positive effect of straw application.3.It can be seen that straw application effectively promotes the accumulation of nutrient elements and improves the quality of rice.Both of chalky rice rate and chalkiness degree decrease significantly on the condition of straw application The amylose content in rice also decreases significantly,but the gel consistency increases significantly.Suitable panicle fertilizer and alternate wetting and moderate drying irrigation can enhance the accumulation of the nutrient elements in grain and soil.Which can improve rice appearance quality and cooking and eating quality.Furthermore,they can significantly promote the positive effect of straw application on rice quality.4.Straw application significantly increases the soil organic matter.It obviously effects the soil physical and chemical properties.Soil pH value is obviously decreased but cation exchange capacity is significantly increased,unit weight of soil is significantly increased while total porosity is significantly increased.After returning straw to the field,the soil bioactivity is significantly enhanced.The urease activity is significantly enhanced and the number of nitrifying bacteria is significantly increased.The application of panicle fertilizer,alternate wetting and moderate drying irrigation can significantly enhance the physiological activity of soil.Furthermore,they can promote the positive effect of straw application.5.Straw application significantly increases methane emission in paddy field.It is showed that the effect of methane emission is mainly concentrated on straw application in pot experiment.In field trial,methane emission is increased by 30%after returning straw to the field.Nitrous oxide emission is affected by straw application with a slight increase but more greatly a:ffected by fertilizer application.The application of panicle fertilizer will result to significant increase nitrous oxide emission.After returning straw to the field,global warming potential(GWP)caused by the increase of greenhouse gas emission is significantly increased in the whole growth period,and the increase of methane emission is the main reason for the increase of GWP.Compared with shallow irrigation,it is obvious that alternate wetting and moderate drying irrigation will reduce methane emission.Furthermore,it can significantly reduce the effect of straw application on greenhouse gas emission.